interesting flaw?!

[cisco-san]

Dear all,

 

I saw on the web a blade with (for me) an interesting flaw (btw. I am not interested on this blade).

What could cause such flaw? Is this an opening of the folded steel or is it just an "optical illusion" (I don´t think so)?

 

Many thanks in advance.

[Ted Tenold]

Klaus,

 

It is my firm belief that this sword is Saiha (retempered). I've outlined another major element seen in some saiha blades which is a product of the re-quenching. The metals expansion and contraction cause surface tension and stress which forms this surface seperation (I hesitate to say "crack" because it's not really the same). I have an image of a retempered blade showing this exact effect and pattern somewhere that I'll dig up and post later.

 

Also note how muddy looking and dull the yakiba is. The habuchi is indistinct and seems to fade away around the machi. If this sword looks like a suriage piece, this will also be a big red flag.

[Ted Tenold]

Here's some images of a sword I have here. The manner in which it was retempered carried the yakiba past the machi and into the sabigawa (rust border) of the nakago. This promoted the look of a sword that was osuriage, pushing the coloration and mizukage effects under habaki area instead of in front of it. Pretty convincing at first glance. I told the owner that it was undoubtedly retempered and asked for permission to polish one side into the nakago to more conclusively show the visual evidence and use this as a demonstration piece. So this is a good opportunity to show it here compared to your image.

 

Note the "V" shaped stress seperations in the same region.

[cisco-san]

Dear Ted,

 

many thanks for your explanation, it is really very helpful.

It is my first time to understand a retempered blade (but I don´t know whats on tomorrow ).

I think you may right that this blade is osuriage, even it is signed - but for sure it is Gimei

 

[Jacques D.]

Hi,

 

even it is signed - but for sure it is Gimei.

 

Before saying that, you could read this